Sunday, January 21, 2007

Here's a quick clip of a plane having a bad gear day. Watch as the pilot shuts down both engines so the propellors don't strike the runway while turning. The only thing he forgot was to switch off the master electric switch - you can see the beacon on the top of the fuselage still blinking.

I had a bad landing gear day a long time ago - I'll write about it tomorrow.

From the news article:

"A twin-engine plane made a belly landing at Arlington Municipal Airport, Texas, late today after apparently having landing gear problems. Both men on board quickly slipped out of the plane. Neither appeared to be hurt. Live TV coverage showed the plane's landing gear did not appear to be fully extended as the Beechcraft circled the airport numerous times. The pilot was able to cut power to the engines as the plane touched the runway, the gear collapsed, the nose went down and the Beechcraft slid on its belly and stopped."


phil said...

ok i'll say it; it's kinda hard to read with the animated avatar.

btw gr8 blog.

Dave Starr said...

FWIW (and I'd certainly appreciate comments from more experienced aviators) I feel shutting down the engines is a case of poor ADM. A year or so ago a fatal accident occurred with this very scenario ... the pilot became apparently so engrossed with shutting down the engines and attempting to reposition the props to minimize damage that the aircraft stalled.

No one would like to be in the position of making this sort of landing but it's my thought it's better to keep the engines alive and touch down with as much control as possible. Yes you'll likely wipe out the props but that's what hull insurance is for ... better than that kind of insurance that only pays after you're dead.

Aviatrix said...

Re the beacon: you can see the pilot catches that too, and goes back to turn the master off after it's clear there is no fire. I wonder what he went back in to shut off after speaking to the firemen. Perhaps the fuel shutoff.

In response to Dave:
There were two of them on board. Even if the second person was not a pilot, the pilot could easily brief "when I say 'now' I want you to pull both those red levers all the way back, and leave them there." I don't believe that was a starter bump that moves the left prop at the end, I think it was just the way it spun down, with one last gasp from the engine.

Wiping out a couple of $5000 propellers isn't the concern so much as wiping out a couple of $50,000 engines. A prop strike on a running engine necessitates a full teardown.

Anonymous said...

Dave, as aviatrix points out, the emergency shutdown on those engines isn't really an involved procedure and it's likely to save a significant amount of money. Not to mention avoid throwing debris that will further damage the plane and possibly the occupants. It also shuts off fuel to the engines which isn't a "bad thing" in this case. It's better to turn the fuel off at the fuel shutoff but every little bit helps. Bumping the starter to get the props safe is probably too much though unless you just have loads of time... which you won't in that airplane.

Phil: Leave Mr. Licky alone. He's cute!

Dave Starr said...

It's good to actually see some discussion here ... and some good thoughts shared as well.

Let me stress my views are not to be critical of any particular pilot's decision making, I'll withdraw my "poor ADM" statement, however, I still say shutting down engines during a gear up landing is not a good idea. Each of us will have to make our own decision should the situation arise.

I also did not say that the pilot in this video spent time trying to bump the props level, I said it was done in another accident with fatal results. I am having a terrible time finding the NTSB report on the one I'm talking about, but I haven't quit looking, yet. I went back and checked some facts with the person who originally reported the accident to me and the facts are different than the video accident we are looking at here. In the fatal accident I was referring to the pilot feathered both engines on short final, bumped the props horizontal and then (apparently never having seen Bob Hoover in action, was supriesed by the aircraft's performance and severely overshot the runway and stalled and spun in while maneuvering. (do you know how far you'll glide gear up with both engines feathered? Wanna become an unpaid test pilot?)

So I'll certainly agree the circumstances of the two incidents differed greatly but the misguided intentions were the same. Mimimize damage to the aircaft by intentinally performing an act to sane pilot otherwise would do, shuttung down all engines and thus relenqishing control while still in the air.

Here's what the AOPA says about intentional gear up landings:

.... If you do end up having to belly in your airplane, be realistic. The idea of trying to stop the prop in a horizontal position, and thereby preventing crankshaft damage to the engine, is dangerous. An airplane has to be flying pretty slow to stop the propeller from rotating, and bumping the propeller with the engine's starter means diverting attention from flying the airplane while low and slow — a situation that is fraught with peril....

Personally I think, like many CFI's I have worked with, that it is much safer to have power available until the last possible moment, if for no other reason than you can touch down at a slower airspeed in relative safety.

Yes I am well aware of the requirements for engine tear-down inspections due to 'sudden stop' or 'prop strike'. The place I learned to fly used wood props on their primary trainers (can you say J-3, yup, l thought ya could) for years because students might nose one up and bust the prop ... but with a wood prop there's no engine tear-down required. However, like most of us even they have now moved into the nose wheel and metal prop era *smile*. Again I'll opine that is what we have insurance for. Hull insurance is based upon underwriter's experience with a fleet, performing a possibly dangerous act merely to save the insurance company exspence is not going to necessarily save any individual any money. The nose falling through without any power to 'catch' it will however certainly be expensive even if not fatal.

A pilot's first and primary job is to bring him/herself and passengers back to earth in safety. Not damaging an aircraft is secondary to that primary purpose. Faced with no other choice a good pilot "uses up" the aircraft to protect the humans involved, rather than go for the "die before embarrassment" model.

If real dead-stick landings were a good idea why wouldn't those in authority demand them of us?

Anonymous said...

Here's another example of a gear-up landing. Unfortunately the quality is not the greatest although I swear I have seen a better version of this landing somewhere else. It is hard for me to point out the moment when he pulls the fuel cutoffs but the propellor is only feathered and fully stopped for about two to three seconds before he touches the ground.

I'm not a pilot but it would seem that the pilot keeps the engines on until the last minute but once he makes the decision to commit to land he pulls the fuel cutoffs and feathers the props.

Like others have mentioned it is also likely that a spinning propeller attached to an operating engine hitting the ground is also a danger of causing damage to other parts of the a/c, not just damaging the engines themselves.

I would guess that perhaps one of the more important parts of cutting the engines is stopping the fuel flow to the engine? If the prop is still spinning slowly when it hits the ground it is likely that it will suffer some damage but stop spinning relatively quickly. But if the engine is still accepting fuel then there is a greater risk of fire?

Just some thoughts.